The U.S. Environmental Protection Agency’s decision Wednesday to block California’s pioneering effort to reduce greenhouse gas emissions from cars is outrageous anddeplorable. It’s further proof that the Bush administration remains blind to what the law, science and good public policy require to combat climate change.

California must challenge this decision vigorously in court, as Gov. Arnold Schwarzenegger has vowed to do. And Congress should step in, if needed, to help overturn it.

The EPA decision stymies efforts by California and 16 other states – which together account for 45 percent of the U.S. auto market – to move ahead with sharply cutting carbon dioxide tailpipe emissions. A 2002 California law would slash emissions from new cars in the state nearly 30 percent by 2016, starting with the 2009 model year. The 16 states are pursuing policies modeled on California’s, but all the states needed a long-delayed waiver from the EPA in order to proceed. California sued the agency in November to force a decision.

In denying the waiver, the Bush administration once again rejected mandatory emissions cuts. EPA Administrator Stephen Johnsonsaid that giving California the green light would have created a “confusing patchwork of state rules” on emissions, and that raising auto fuel efficiency standards under a new federal energy law is sufficient. But that’s hogwash.

Here’s why the EPA decision was flawed:

• First, it ignored legal precedent. Under the Clean Air Act, California can set its own tougher-than-federal standards on vehicle emissions if it obtains a federal waiver. Over the past 40 years, the EPA has granted California about 50 waivers covering various pollutants, while denying none. The act also acknowledges the right of other states to adopt California’s standards.

• Second, it ignored recent federal court rulings. The U.S. Supreme Court in April concluded that greenhouse gases are pollutants that can and should be regulated under the Clean Air Act. Two other federal courts have since reinforced states’ rights to proceed with their clean car rules.

• Third, it ignored public health and environmental needs. California’s clean vehicle standards would eliminate greenhouse gases equivalent to taking 6.5 million cars off the road by 2020. If the other 16 states followed through, that would grow to nearly 22 million vehicles. Scientists say the United States must move quickly to cut emissions 15 to 20 percent by 2020 and 80 percent by 2050 to ward off the worst damage from climate change.

The EPA used the new, higher auto fuel economy standards as a convenient excuse to deny action on tailpipe emissions. Tougher mileage standards are a big step forward, but they don’t represent a comprehensive approach. This disastrous decision must not be allowed to stand.